Electromagnet with removable armature guide of hard material



Patented June 10, 1952 stares rarel oFFicE ELECTROMAGNET WITH'REMOVABLE AR MATURE GUIDE OF HARD MATERIAL Charles-R. Mikolic and ocean. Beling, Milwaukee, Wis, assignors to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application June 9, 195 0, Serial No. 167,162

4 Claims.

This invention relates in general toelectromag-nets and in particular to the movable armatures of such electromagnets.

Prior art devices of this type sometimes uti- .lize hard, nonmagnetic material deposited by welding on the armature to provide a wearing surface for the armature against the guideways in which the armature moves.

The use of such a welded deposit has the disadvantages that the welding operation is expensive and time consuming and that a grinding operation is necessary after welding to remove excess weld material. A further disadvantage of .these welded devices is that because the wearing member is usually :a wedge-shaped deposit with a fiat surface .of the wedge providing the wearing surface, there exists the possibility of excessive wear and binding due to misalignment of the plane surface .of the wearing member against the guideways.

An additional disadvantage of welded memhers is that in case of damage to the wearing member, .it is extremely difficult to remove the member for salvage of the remainder of the armature.

These disadvantages can be overcome by utilizing bars of hard, nonmagnetic material loosely inserted in the sides of the armature and of. such shape as to provide line contact wearing surfaces for the armature. One of the mostsuitableforms of such a member is cylinvdriclalhars of hard material removably inserted ingrooves on the sides of the armature adjacent the gu'ideway's' in which the armature moves. 7

It is therefore .an object of the invention to provide an electromagnet having an armature provided with inserts of hard, nonmagnetic material in' which such inserts are removable.

It is a further object of this invention to provide an improved electromagnet having an armature provided with wearing surfaces which makeia line contact with theguidewaysin which the armature is movable.

It isflafurther object of this invention to provide tan. electromagnet armature having bars of hard, nonmagnetic material loosely inserted in groovesin the sides thereof in which the configuration vof the grooves prevents movement of the bars'laterally of the grooves.

Objects and advantages other than those outlined above will be readily apparent from the following detailed description when read in connection" with the accompanying drawing, in

which:

secured together by rivets I2.

coil 21.

,Fig. 1 is a side view, partly in cross section, of an electromagnet embodying the preferred form of the present invention; Fig. 2 is a sectional view taken along line II-II of Fig. 1,;

Fig". 3 is a side view on an enlarged scale, of a portion of the armature of the electromagnet shown in Fig. 1, with an armature end plate removed;

Fig. 4 is a view similar to Fig. 3 illustrating an alternate embodiment of the invention;

Fig. 5 is a sectional view taken along line VYV of Fig. 4; and

Fig. 6 is a view similar to Fig. 4 illustrating another embodiment of the invention.

As shown in Figs. 1 and 2, the electromagnet utilizing this invention may comprise a suitable core, such as the generally E-shaped core I shown, havinga middle leg 8 and two outer legs 9', H. Core I may be of one solid piece or may be composed of a plurality of .E-shaped laminations reinforced by a pair of end plates l0 and The core I is secured to pairs of upright supporting members I13, .14 by pairs of plates l5, I6 secured there'- to and to core I by screws ll. Members l3,- M

are secured to a base member [B to provide a rigid mounting for the electromagnet. A suitable energizing coil 2! may be mounted. on

middle leg B'to' cause the latter to form a pole for .the magnet. Coil 2| is mounted on core I .by a pair of supporting bars 22, 23, secured to core I by screws 24. Spacers 25 inserted between .coil H and core 1 insure rigid mounting of the coil on the core.

form ,guideways for guiding the movement of armaturezfi' and the armature is provided with the removable bars.

The shank of armature 26 is provided with an axial recess to receive theendof a push rod 21 which is secured to armature 26 by a bolt 28 screwed into rod 21. Push rod 21 extends through an opening in the middle leg 8' of core I and is connected to a suitable device to be actuated (not shown), such as the movable contacts of an electric switching device. When coil 21 is deenergized, armature 26 is in a low ered position shown in Figs. 1 and 2, and upon energization of coil 2|, armature 26 is attracted toward middle leg 8 to lift push rod 21. Base I8 may be provided with a pair of blocks 29 of suitable shock absorbing material such as rubber to reduce the vibration of the assembly upon deenergization of coil 2i and release of armature 26.

Armature 26 may be one solid piece but is preferably composed of a plurality of T-shaped laminations. Some of the laminations, and preferably all of them, are provided with an indentation on each side of the head portion thereof. In the preferred embodiment illustrated in Figs. 1 to 5, the indentations 31 are formed as segments of circles. The indentations 3| on each side of each lamination are aligned to form two grooves on the sides of the armature adjacent the guideways. The grooves may extend in any direction relative to the direction of movement of the armature but preferably extend perpendicularly thereto as shown on the drawing. Into each of these grooves is inserted a round bar 34 of hard, Wear resistant material such as the chromium-cobalt-tungsten alloy sold under the trade-mark Stellite. The bars 34 are preferably nonmagnetic so as to provide balanced air gaps to reduce magnetic side thrust between surfaces I9, 23 and surfaces 32, 33, and thereby decrease the possibility of binding or sticking of the armature.

When the bars 34 are inserted in the grooves, a portion of the bars 34 projects beyond the surfaces [9 and of armature 23 and is in contact with guideways 32, 33 to provide wearing surfaces for the armature. The bars 34 are preferably loosely or nonrigidly mounted in the grooves as shown in Fig. 3, so as to be free to rotate therein, but may be press fitted into the grooves, as in the embodiment illustrated in Figs. 4 and 5. If the bars 34 are to be press fitted into the grooves, the ends of the bars are preferably slightly chamfered, as shown in Fig. 5, to aid in inserting the bars in the grooves.

The configuration of the indentations provides lip portions on the armature laminations, which overlie bars 34 and prevent movement of bars 34 laterally of the grooves. Suitable means are also provided to prevent movement of bars 34 longitudinally of the grooves, such as plates secured over each end of each groove, preferably in the form of T-shaped end plates 35 of the same size as the laminations of armature 26, but not provided with indentations, secured to each end of the armature. The armature assembly comprising bars 34, the armature laminations and plates 35 are held together by rivets 36.

The use of round bars 34 provides a line contact for the bars on guideways 32, 33, thereby greatly decreasing the friction between the armature and the guideways and reducing the possibility of binding and excessive Wear on the bars. If the round bars 34 are rotatably mounted in the grooves as shown in Fig. 3, movement of armature 26 causes bars 34 to rotate to thereby provide a varying wearing surface on the bars and prevent the bars from becoming flattened on one portion of the periphery thereof after considerable use.

In the embodiment illustrated in Fig. 6, the armature laminations are provided with polygonal indentations 38 on each side of the head portion thereof. The grooves formed by aligned indentations 38 receive square bars 31 of material similar to the material of bars 34, and bars 31 are prevented from moving longitudinally of the grooves by end plates 35-. The configuration of indentations 3B prevents movement of bars '31 laterally of the grooves, and the point at which two adjacent sides of bars 31 meet provides line contact wearing surfaces on each side of armature 26 on the guideways. If desired, round bars 34 may be inserted in the grooves formed by polygonal indentations 38, bars 34 then being free to rotate in the grooves to provide Varying wearing surfaces for the armature.

Although only round and square bars have been illustrated, it will be obvious to those skilled in the art that many other shapes of bars, such as triangular or oval, may be used without departing from the spirit of the invention as set forth in the claims.

It is claimed and desired to secure Patent:

1. An electromagnet comprising a core, an energizing coil for said core, an armature movable in response to energization of said coil, guideways in said core for guiding the movement of said armature, said armature being composed of laminations provided with indentations, said indentations being aligned to form two grooves on the sides of said armature adjacent said guideways, round bars of hard, nonmagnetic material loosely inserted in said grooves in rolling contact with said guideways to provide line contact wearing surfaces for said armature during said movement, the cross sectional configuration of said grooves being substantially that of a segment of a circle greater than a semicircle, said sides of said armature forming the chord of said circle, and means secured over the ends of said grooves for preventing movement of said bars longitudinally of said grooves, said bars being free to rotate to thereby provide varying wearing surfaces for said armature and to provide nonmagnetic spacers between said armature and said guideways.

2. An electromagnet comprising a core, an energizing coil for said core, an armature movable in response to energization of said coil, guideways in said core for guiding the movement of said armature, said armature being composed of laminations provided with polygonal indentations, said indentations being aligned to form two grooves on the sides of said armature adjacent said guideways, the sides of said armature and the inside surfaces of said grooves forming edges, polygonal bars of hard, nonmagnetic material inserted in said grooves in contact with said guideways to provide line contact wearing surfaces of said armature during said movement and to provide nonmagnetic spacers between said armature and said guideways, the sides of each of said edges forming an angle less than degrees to prevent movement of said bars laterally of said grooves, and means secured over the ends of said grooves for preventing movement of said bars longitudinally of said grooves.

3. An electromagnet comprising a core, an energizing coil for said core, an armature movable in response to energization of said coil, guideways in said core for guiding the movement of said armature, said armature being composed of laminations provided with indentations'said indentations being aligned to form two grooves on the sides of said armature adjacent said guideby Letters ways, the sides of said armature and the inside surfaces of said grooves forming edges, and bars of hard, nonmagnetic material removably inserted in said grooves in contact with said guideways to provide line contact wearing surfaces for said armature during said movement and to provide nonmagnetic spacers between said armature and said guideways, the sides of each of said edges formed in said armature by said grooves forming an angle less than 90 degrees to prevent movement of said bars laterally of said grooves.

4. An electromagnet comprising a generally E-shaped core having a middle leg and a pair of outer legs, an energizing coil mounted on said middle leg, a generally T-shaped armature movable in response to 'energization of said coil, said outer legs forming guideways for guiding the movement of said armature, said armature being composed of a plurality of T-shaped laminations and each of said laminations being provided with indentations, said indentations being aligned to form a pair of grooves disposed on the sides of the head portion of said armature facin said guideways, the sides of said armature and the inside surfaces of said grooves forming edges, and bars of hard, nonmagnetic material inserted in said grooves in contact with said guideways to provide line contact wearing surfaces for said armature during said movement and to provide nonmagnetic spacers between said armature and said guideways, the sides of each of said edges formed in the armature by said grooves forming an angle less than 90 degrees to prevent movement of said bars laterally of said grooves.

CHARLES R. MIKOLIC. ,GEERT D. BELING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 420,138 Wood Jan. 28, 1890 1,226,697 Rinsche May 22, 1917 1,265,027 Alldread May 7, 1918 1,293,052 Dinsmoor Feb. 4, 1919 1,696,615 Trombetta Dec. 25, 1928 2,239,267 Jeffrey Apr. 22', 1941 2,363,117 Butler Nov. 21, 1944 2,480,057 Soreng Aug. 23, 1949 FOREIGN PATENTS Number 'Country Date 457,540 Great Britain May 31, 1935 

